There are many types of connectors for making circuit and hydraulic connections in hostile environments such as under water. The majority of these known connections must be made in a controlled environment prior to exposure to the hostile environment. With the advent of rapid growth in oceanographic exploration, it has become necessary to provide underwater electrical, optical and hydraulic equipment which is both reliable and relatively inexpensive and easy to work with while underwater. Underwater circuit connectors for interconnecting cables and hoses are an essential component in many underwater systems such as offshore oil drilling platform systems and defense sector applications. The reliability of these connectors is critical because a failed connector can cause serious adverse effects on the operation of the sub-sea system. Common causes of connector failure include corrosion due to cathodic effects, the salt water environment, the inability to isolate the circuit contacts from the environments, designs which allow tolerances of multiple dimensions to become additive causing the connector to exceed specification or designs, all of which present potential problems for a diver, or automated means, attempting assembly or decoupling of a connector. There have been improvements in corrosion resistance of connectors as the art has developed but there is still a need for a more easily assembled connector that will not fatigue and which has a simple, design that is inexpensive to manufacture. Connectors in the past have relied mainly on an interference or compression of resilient members for sealing of internal components. Past connectors also have been limited in the number of circuits which can be utilized in the connector.
One category of connectors includes connectors intended for sub-sea mating and demating and offers the ability to mate and demate circuits under water. Such underwater connectors typically comprise a receptacle or female connector connected to one cable end and a plug or male connector connected to the other cable end and designed for mating engagement with the receptacle. These parts must be designed such that they can be connected underwater, and can be repeatedly mated and demated underwater. In one type of underwater connector, the circuits are isolated from the environment by having the receptacle socket filled with dielectric fluid or a semi-mobile compound. The female portion (or receptacle) contains electrical or optical contacts within a sealed hermetic chamber. The male portion (or plug) has one or more contact probes exposed to the environment prior to engagement. The probe(s) enter the sealed hermetic chamber and contact the female contact elements in the sealed receptacle chamber to make the connection.
Historically these types of connectors are precision machined mechanical devices which utilize complex sealing mechanisms to contain the protective medium yet allow mating of the connector circuits. Costs associated with the manufacture of these devices are substantial, and have typically resulted in selling prices of such magnitude that the utilization of these products has been limited to only the most critical of systems.
The major problem with past under water connectors, which has resulted in the expensive, complicated sealing mechanisms, has been ensuring that seawater cannot enter the connection chamber and that fluid in the connection chambers can not leak out, especially over time. The longevity of many current systems is questionable due to the "cold set" of seals such that the seals become inflexible due to loss of memory and are no longer able to function properly.
Several general types of different sealing mechanisms have been devised in the past for sealing the connectors as the connection is made. One such sealing mechanism has an opening into the mating/connection chamber which comprises an elastomeric tubular entrance surrounded by an elastomeric sphincter that pinches the entrance closed upon itself, in the unmated condition. In the mated condition, the sphincter pinches against the entering probe. Although this type of seal is successful in some cases, it does have some drawbacks. One drawback is that seals of this type do not work well in all conditions. Another drawback is that such seals will lose their "memory" after they have been mated and demated a number of times, and will then fail to close quickly enough to isolate the chamber from the surrounding environment.
There are various other means for assuring isolation of the contacts from the environment. Some existing means for isolation, used in various different connectors, include rotating seal valves, tubular socket contacts in the receptacle unit, and spring-biased pistons which are urged into sealing engagement with the open ends of the sockets. In the piston arrangement, as the plug and receptacle units are mated, pins on the plug portion urge the pistons back past contact bands in the sockets, so that electrical contact is made. However, this type of arrangement can not be used in an optical connector since the optical contacts must be able to engage axially for practical purposes.
To date, the known mechanisms for providing optical and electrical connections in a hostile environment are not completely effective. Additionally, the optical connectors available are expensive, and generally require complicated means for terminating the connector elements to the transmission cables they are intended to connect. The presently known connectors can not provide an inexpensive connector for making reliable and repeatable optical and electrical connections in hostile environments such as great ocean depths, outer space, or outdoor environments.
A subcategory of connectors intended for subsea mating and demating, includes connectors that are fluid filled and pressure balanced. In general, fluid filled connectors have a closed chamber wherein there is an oil filled chamber with an opening which is sealed by a spring-biased slidable shuttle piston arranged to be pushed back by engagement of a projecting male contact pin with the piston. In the unmated condition, the opening seals against the elongate section of a piston contained within the receptacle socket assembly, and resiliently biased outwardly so as to follow the male probe into the opening as the probe is withdrawn. The opening is always sealed, either by being filled with the piston, or with the male probe. By providing a shuttle piston, very little, if any distortion of the opening is required, and the opening can be quite large to permit large pin diameters for heavy current and/or a multi service arrangement such as coaxial connection. The opening of the chamber is closed either by the shuttle position in the unmated condition of the connector, or by the male contact pin when the male and female parts of the connector are brought together. A seal for the opening is provided in the form of a pair of spaced o-rings for engaging the shuttle piston or the contact pin, depending on which of these extends through the opening.
The intention of the fluid filled connectors is to protect the electrical junctions from the outside environment by enclosing them within a chamber of benign, non-conductive, mobile, dielectric substance such as oil, gel, or grease, from which seawater is excluded. These types of connectors are also spark-proof. They can be mated and demated with the receptacle sockets electrically energized. Any arcing is contained within the oil filled chamber and is partially suppressed by the oil. Therefore these types of connectors could be used in volatile atmospheres without danger of spark-induced explosions. However, many of these connectors are relatively large, and can not accommodate a large number of electrical contacts, and are limited therefore in their uses. Nor are the pin contacts in the plug of many of these current connectors protected from the environment in the unmated condition, resulting in contact corrosion and failure.
With this arrangement, (having the probe contacts exposed to the atmosphere) there is a risk of deterioration of the seal which may result in water or contaminants entering the chamber where the electrical connection is made. Thus, there were developed connectors with two chambers, one before or outside of the second, such that if the seal on the first chamber weakened, the seal on the second chamber would still maintain the isolation of the electrical contact from the contaminating environment that penetrated the first chamber.
With interference type seals or o-ring sealing members, as the connectors, mated or unmated, are lowered into the sea and subjected to greater and greater pressures, a differential pressure builds up across the sealing means and eventually the seal may fail and water enter the connectors. In response to this problem there were developed connectors that eliminated differential pressures across the sealing means of the connector. One type of such connector has resiliently deformable conduits which, when subjected to pressure, increase the pressure of the nonconducting fluid within the connector against o-ring seals so that the pressure of the nonconducting fluid within the conduit and the housings equals the pressure of the seawater external to the housings. Since there is little or no differential pressure across the o-ring seals sea water will not enter the plug or receptacle housing. Since the conduit is resiliently compressible, as the cable and connector assembly go to greater depths and the sea water pressure against the conduit increases, the conduit compresses, thereby increasing the pressure of the nonconducting fluid so as to prevent seawater from entering into the connector assembly through the o-ring seals.
Also, in many known connectors capable of underwater connection, the power must be turned off when it is desired to break contact of the circuit because if the connections are left powered and unconnected, and seawater enters the connectors, electrolytic action will take place causing corrosion. Thus some connectors can not be left in place while disconnected with the power on. This is major drawback for undersea operations.
Thus there is the need for electrical, fiber optic, hybrid electro-optical, hydraulic and gas connectors that can be installed relatively easily in the field, yet are reliable, and that can be repeatedly mated and demated in a number of hostile environments such as under water, outer space or volatile environments. However, the previous connectors have various shortcomings, some of which have been discussed above, such as failing of the sealing mechanism of o-rings or openings in an elastomeric material. Other connectors use complicated adjacent plates that must be rotated to align passages through the plates, or gates that must be aligned, in order for the probe to enter the receptacle, all of which introduce moving parts that must be manufactured, manipulated correctly and which can fail. Another particular shortcoming is that the connectors are often extremely expensive and generally require complicated means for terminating the connector elements to the optical or electrical cables they are intended to eventually connect. Thus, many connectors, while reliable, are complicated and expensive. Some are also not easily adaptable for fiber optic or other types of connections.
Therefore it would be desirable to have a high performance connective device similar in purpose to the currently available connectors, and which could be repeatedly mated and demated in hostile environments, but which could be offered at a substantially lower price, and which would have a number of uses by being of a simple general design, without complicated mechanical parts that could easily fall, and which would provide flexibility and adaptability of use in many applications.